Chemical process scientists and engineers have been continuously studying the subject of manufacture of amines by the amination of olefins. This has also been the subject matter of many patents. Continuous improvements have been made over several years of research, but there is still a tremendous scope to improve yield, conversion rates and in choice of catalyst.
U.S. Pat. Nos. 4,307,250 and 4,375,002 to Peterson et al claims a process for vapor phase catalytic amination for the production of amines wherein an olefin is reacted at a temperature and pressure sufficient to effect formation of the amine, but controlled to prevent polymer formation. The temperature is from 200 degree C.-450 degrees C. and the pressure from 300-6,000 psig using an alumino silicate, e.g. a zeolite catalyst. The selectivity obtained is greater than 95% and the conversion is 3-20%.
EP 0305564 pertains to an improved catalytic process for the amination of C 2-8 olefins, the catalyst being a dealuminized zeolite having an increased Si:Al molar ratio over original zeolite. The dealuminized H-mordenite catalyst is particularly effective for the amination of isobutylene to give tert-butyl amine, at a pressure of 600-1100 psig.
U.S. Pat. No. 6,809,222 (EP1289925) discloses and claims aliphatic amines that are obtained by continuous addition of ammonia to C2 to C8 alkenes (specifically isobutylene) in the presence of a heterogeneous or homogeneous catalyst such as zeolite catalyst like ZSM-5-type at a pressure of 300-1200 psig [2 to 8 MPa] [20-80 bar], a temperature of 220 to 320° C. and a molar ratio of ammonia to the alkene of 1.5 to 20. The conversion of isobutylene to tert-butylamine is 5% and the selectivity is 99.5%. The ratio of silica to alumina is not mentioned.
An article titled “Amination of butanes over protonic zeolites” by M. Lequitte et. al; published in Journal of Catalysis of October 1996, Vol 163, Issue 2, page 255-261 investigated the reaction of 1-butene and isobutene with ammonia. Several zeolites were compared in standard conditions (molar ratio ammonia/olefin=1, total pressure 4 MPa, 600 psig) at different temperatures. The major product of the reaction of isobutene is tert-butylamine, which is formed with high selectivity at low temperature. In the conditions of reaction (4 MPa), the thermodynamic equilibrium at 250° C. is about 20% conversion into tert-butylamine.
CA2092964 relates to method for preparation of alkylamines comprising reacting ammonia or an amine and an olefin containing 2 to 10 carbon atoms per molecule wherein the olefin is isobutylene, in a molar ratio of from 1:1 to 10:1 preferably 2:1, in the presence of a catalyst comprising a zeolite beta having silica-alumina molar ratio of 10:1 to 100:1 at a temperature of 100° C. to 350° C. specifically 260° to 300° C. and a pressure of (68.95-344.74 bar) 1000 psig to 5000 psig preferably 1500 psig to 3500 psig and a liquid hourly space velocity of 0.1 to 10.0 h−1.